This invention relates generally to video encoding and more specifically to determining number of transmitted data bits to balance image quality and motion smoothness.
The flexibility of a Fine-Granular Scalability (FGS) video encoding enables it to support a wide range of transmission bandwidths as is described in U.S. Pat. No. 6,501,797B1, entitled xe2x80x9cSystem and Method for Improved Fine Granular Scalable Video Using Base Layer Coding Informationxe2x80x9d filed on Jul. 6, 1999, and assigned to the assignee herein. An improved FGS video encoding method is disclosed in U.S. Pat. No. 6,639,943, entitled xe2x80x9cHybrid Temporal-SNR Fine Granular Scalability Video Coding,xe2x80x9d filed on Jun. 9, 2000 and assigned to the assignee herein. In the hybrid temporal-SNR (Signal-to-Noise Ratio) FGS video encoding method disclosed, the encoder is operable to encode video images into an SNR FGS only format or a hybrid temporal-SNR FGS format. A determination is made whether to transmit only SNR (i.e., quality) FGS encoded video data in a frame or to transmit hybrid temporal-SNR encoded video data in a frame. In the former case, a high quality image is transmitted as all the available bandwidth is utilized by data bits that contribute to the image quality, while in the latter case, the available bandwidth is occupied by data bits to enhance image quality and data bits to smooth object motion. When encoded video images are transmitted in the high quality first mode objects within the frame exhibit a xe2x80x9cjerkyxe2x80x9d motion, while encoded video images transmitted in the second mode are of a lower quality. A disadvantage of this method is that once a mode is selected, the selected mode is not changed during the transmission. Hence, when the second mode of transmission is selected, a lower quality image is transmitted, even when there is no object motion from frame-to-frame.
An efficient use of the available network bandwidth is accordingly not achieved with the transmission mode selection method, as the transmission mode is not adapted to the video images.
Hence, a method or system is needed for determining a transmission mode that makes efficient use of and accommodates changes in transmission bandwidth and image motion from frame to frame in order to balance the received image quality and image object motion smoothness.
In a Fine Granular Video encoding system, a method for determining the number of transmission bits of encoded SNR and temporally enhanced video data to balance image quality and object motion is presented. In accordance with the principles of the invention, a number of transmission bits at a known bit-rate for each of a quality enhanced video image frame and a temporal enhanced video image frame is determined, in one aspect by, comparing a ratio of a measure of quality enhanced frame data and a measure of quality enhanced frame data and temporally enhanced frame data to a known threshold. The number of bits transmitted in each of the quality enhanced frame and the temporally enhanced frame is then determined using a first method when the ratio is above the known threshold and using a second method otherwise.